How do you open the doors?

Bash with 18/00 str.

Ah I see, so that works as well.

Does that really work for you?
I've tried it once and the number of times you have to bash a lock to open it got tiresome really fast.

Another alternative to picking locks could be the knock spell.

Still, I value the convenience of the thief skills too much to get rid of them.
Even if it's just a human that thief dualclasses from thief to something else at level 6 or 7 (i.e. enough thief leves to max the lockpicking and trap skills).